Apply ROT13 or a custom Caesar shift to letters while preserving punctuation and spacing.
Mode
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Shift
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Letters changed
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Enter the example value or paste your own input, choose the mode when one is available, and read the first result card for the direct answer. The output area gives a copyable block for code reviews, documentation, API tests, classwork or troubleshooting notes.
What the result means
ROT13 is a Caesar shift of 13. Custom mode lets students and developers test the simple substitution rule.
What is not included
This is a learning and puzzle cipher. It is not encryption for private or sensitive data.
Privacy note
The calculation runs in your browser. Avoid pasting production secrets, credentials, private keys, customer data or regulated personal data unless your own policy allows browser-based tools.